/*
 * Copyright (C) 2005-2013 MaNGOS <http://getmangos.com/>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "spline.h"
#include <sstream>
#include <G3D/Matrix4.h>

namespace Movement
{

SplineBase::EvaluationMethtod SplineBase::evaluators[] =
{
    &SplineBase::EvaluateLinear,
    &SplineBase::EvaluateCatmullRom,
    &SplineBase::EvaluateBezier3,
    (EvaluationMethtod)& SplineBase::UninitializedSpline,
};

SplineBase::EvaluationMethtod SplineBase::derivative_evaluators[] =
{
    &SplineBase::EvaluateDerivativeLinear,
    &SplineBase::EvaluateDerivativeCatmullRom,
    &SplineBase::EvaluateDerivativeBezier3,
    (EvaluationMethtod)& SplineBase::UninitializedSpline,
};

SplineBase::SegLenghtMethtod SplineBase::seglengths[] =
{
    &SplineBase::SegLengthLinear,
    &SplineBase::SegLengthCatmullRom,
    &SplineBase::SegLengthBezier3,
    (SegLenghtMethtod)& SplineBase::UninitializedSpline,
};

SplineBase::InitMethtod SplineBase::initializers[] =
{
    &SplineBase::InitCatmullRom,    // we should use catmullrom initializer even for linear mode! (client's internal structure limitation)
    &SplineBase::InitCatmullRom,
    &SplineBase::InitBezier3,
    (InitMethtod)& SplineBase::UninitializedSpline,
};

///////////
#pragma region evaluation methtods

using G3D::Matrix4;
static const Matrix4 s_catmullRomCoeffs(
    -0.5f, 1.5f, -1.5f, 0.5f,
    1.f, -2.5f, 2.f, -0.5f,
    -0.5f, 0.f,  0.5f, 0.f,
    0.f,  1.f,  0.f,  0.f);

static const Matrix4 s_Bezier3Coeffs(
    -1.f,  3.f, -3.f, 1.f,
    3.f, -6.f,  3.f, 0.f,
    -3.f,  3.f,  0.f, 0.f,
    1.f,  0.f,  0.f, 0.f);

/*  classic view:
inline void C_Evaluate(const Vector3 *vertice, float t, const float (&matrix)[4][4], Vector3 &position)
{
    Vector3 tvec(t*t*t, t*t, t);
    int i = 0;
    double c;
    double x = 0, y = 0, z = 0;
    while ( i < 4 )
    {
        c = matrix[0][i]*tvec.x + matrix[1][i]*tvec.y + matrix[2][i]*tvec.z + matrix[3][i];

        x += c * vertice->x;
        y += c * vertice->y;
        z += c * vertice->z;

        ++i;
        ++vertice;
    }

    position.x = x;
    position.y = y;
    position.z = z;
}*/

inline void C_Evaluate(const Vector3* vertice, float t, const Matrix4& matr, Vector3& result)
{
    Vector4 tvec(t * t * t, t * t, t, 1.f);
    Vector4 weights(tvec * matr);

    result = vertice[0] * weights[0] + vertice[1] * weights[1]
             + vertice[2] * weights[2] + vertice[3] * weights[3];
}

inline void C_Evaluate_Derivative(const Vector3* vertice, float t, const Matrix4& matr, Vector3& result)
{
    Vector4 tvec(3.f * t * t, 2.f * t, 1.f, 0.f);
    Vector4 weights(tvec * matr);

    result = vertice[0] * weights[0] + vertice[1] * weights[1]
             + vertice[2] * weights[2] + vertice[3] * weights[3];
}

void SplineBase::EvaluateLinear(index_type index, float u, Vector3& result) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    result = points[index] + (points[index + 1] - points[index]) * u;
}

void SplineBase::EvaluateCatmullRom(index_type index, float t, Vector3& result) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    C_Evaluate(&points[index - 1], t, s_catmullRomCoeffs, result);
}

void SplineBase::EvaluateBezier3(index_type index, float t, Vector3& result) const
{
    index *= 3u;
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    C_Evaluate(&points[index], t, s_Bezier3Coeffs, result);
}

void SplineBase::EvaluateDerivativeLinear(index_type index, float, Vector3& result) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    result = points[index + 1] - points[index];
}

void SplineBase::EvaluateDerivativeCatmullRom(index_type index, float t, Vector3& result) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    C_Evaluate_Derivative(&points[index - 1], t, s_catmullRomCoeffs, result);
}

void SplineBase::EvaluateDerivativeBezier3(index_type index, float t, Vector3& result) const
{
    index *= 3u;
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    C_Evaluate_Derivative(&points[index], t, s_Bezier3Coeffs, result);
}

float SplineBase::SegLengthLinear(index_type index) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);
    return (points[index] - points[index + 1]).length();
}

float SplineBase::SegLengthCatmullRom(index_type index) const
{
    MANGOS_ASSERT(index >= index_lo && index < index_hi);

    Vector3 curPos, nextPos;
    const Vector3* p = &points[index - 1];
    curPos = nextPos = p[1];

    index_type i = 1;
    double length = 0;
    while (i <= STEPS_PER_SEGMENT)
    {
        C_Evaluate(p, float(i) / float(STEPS_PER_SEGMENT), s_catmullRomCoeffs, nextPos);
        length += (nextPos - curPos).length();
        curPos = nextPos;
        ++i;
    }
    return length;
}

float SplineBase::SegLengthBezier3(index_type index) const
{
    index *= 3u;
    MANGOS_ASSERT(index >= index_lo && index < index_hi);

    Vector3 curPos, nextPos;
    const Vector3* p = &points[index];

    C_Evaluate(p, 0.f, s_Bezier3Coeffs, nextPos);
    curPos = nextPos;

    index_type i = 1;
    double length = 0;
    while (i <= STEPS_PER_SEGMENT)
    {
        C_Evaluate(p, float(i) / float(STEPS_PER_SEGMENT), s_Bezier3Coeffs, nextPos);
        length += (nextPos - curPos).length();
        curPos = nextPos;
        ++i;
    }
    return length;
}
#pragma endregion

void SplineBase::init_spline(const Vector3* controls, index_type count, EvaluationMode m)
{
    m_mode = m;
    cyclic = false;

    (this->*initializers[m_mode])(controls, count, cyclic, 0);
}

void SplineBase::init_cyclic_spline(const Vector3* controls, index_type count, EvaluationMode m, index_type cyclic_point)
{
    m_mode = m;
    cyclic = true;

    (this->*initializers[m_mode])(controls, count, cyclic, cyclic_point);
}

void SplineBase::InitLinear(const Vector3* controls, index_type count, bool cyclic, index_type cyclic_point)
{
    MANGOS_ASSERT(count >= 2);
    const int real_size = count + 1;

    points.resize(real_size);

    memcpy(&points[0], controls, sizeof(Vector3) * count);

    // first and last two indexes are space for special 'virtual points'
    // these points are required for proper C_Evaluate and C_Evaluate_Derivative methtod work
    if (cyclic)
        points[count] = controls[cyclic_point];
    else
        points[count] = controls[count - 1];

    index_lo = 0;
    index_hi = cyclic ? count : (count - 1);
}

void SplineBase::InitCatmullRom(const Vector3* controls, index_type count, bool cyclic, index_type cyclic_point)
{
    const int real_size = count + (cyclic ? (1 + 2) : (1 + 1));

    points.resize(real_size);

    int lo_index = 1;
    int high_index = lo_index + count - 1;

    memcpy(&points[lo_index], controls, sizeof(Vector3) * count);

    // first and last two indexes are space for special 'virtual points'
    // these points are required for proper C_Evaluate and C_Evaluate_Derivative methtod work
    if (cyclic)
    {
        if (cyclic_point == 0)
            points[0] = controls[count - 1];
        else
            points[0] = controls[0].lerp(controls[1], -1);

        points[high_index + 1] = controls[cyclic_point];
        points[high_index + 2] = controls[cyclic_point + 1];
    }
    else
    {
        points[0] = controls[0].lerp(controls[1], -1);
        points[high_index + 1] = controls[count - 1];
    }

    index_lo = lo_index;
    index_hi = high_index + (cyclic ? 1 : 0);
}

void SplineBase::InitBezier3(const Vector3* controls, index_type count, bool /*cyclic*/, index_type /*cyclic_point*/)
{
    index_type c = count / 3u * 3u;
    index_type t = c / 3u;

    points.resize(c);
    memcpy(&points[0], controls, sizeof(Vector3) * c);

    index_lo = 0;
    index_hi = t - 1;
    // mov_assert(points.size() % 3 == 0);
}

void SplineBase::clear()
{
    index_lo = 0;
    index_hi = 0;
    points.clear();
}

std::string SplineBase::ToString() const
{
    std::stringstream str;
    const char* mode_str[ModesEnd] = {"Linear", "CatmullRom", "Bezier3", "Uninitialized"};

    index_type count = this->points.size();
    str << "mode: " << mode_str[mode()] << std::endl;
    str << "points count: " << count << std::endl;
    for (index_type i = 0; i < count; ++i)
        str << "point " << i << " : " << points[i].toString() << std::endl;

    return str.str();
}

}
